Citharinus citharus, Heterobranchus bidorsalis, Synodontis clarias and Heterotis niloticus were examined for Endoparasites from June to January. A sample size of 160 fish each, for the four fish species were analysed. Two species of parasites were recovered; Eustrongylides sp (Nematode) and D. latum (Cestode). Eustrongylides sp. was prevalent > 90% in all the fish species. All the parasites were recovered from the gastrointestinal tract. Synodontis clarias had the highest mean parasites load of 5.27.78±0.75 in the stomach and 2.85±0.49 in the intestine during the dry season.

1. Asian Journal of Basic Science & Research
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ISSN: 2582-5267 www.ajbsr.net
37
Seasonal Variation in Endoparasite Loads in Four Fish Species from
Lower River Benue, Makurdi Nigeria
Research Article Country: Nigeria
Introduction
Fish production and productivity is affected by several factors including parasites. They are
host to diverse parasites and their infections significantly affect fish behaviour, metabolism,
body condition, fecundity or survival (Lafferty 2008). In a fish community, different fish
species can exhibit broad variation in sensitivity to parasite infection. Three major factors
play essential roles in host vulnerability and infection levels among fishers; host-parasite
co-evolution, exposure to parasites and host suitability (Holmes, 1990). Others are
temperature, increase in organic matter, pH and oxygen.
Also, seasons have varied effects on parasites infections, both prevalence and intensity.
Seasons are associated with rainfall intensity, variation in pollutant, abundance of insects,
flood, increase in domestic sewage (Hammida, 1991). Rainfall intensity may lead to
Eutrophication which raises the level of intermediate hosts, which are food to fish. It
increases parasitism in fish. This study is aimed at investigating variation of body
parameters and parasite load by seasons.
Materials and Methods
Experimental Site
Fish were sampled from June to January at Ijaha I and II, modern market ward landing site
and Wadata market all situated along River Benue at Makurdi, Benue State. The state is
located in the Southern Guinea Savannah of Nigeria. The river is a major tributary of river
Niger. Its’ own tributaries are Rivers Katsina –Ala and Donga.
Makeri, V.A.1
, Annune, P.A.2
& Cheikyula, J.O.2
1
Akperan Orshi College of
Agriculture, Yandev, Nigeria.
2
Department of Fisheries and
Aquaculture, Federal University of
Agriculture, Makurdi, Nigeria.
Corresponding Author
Author Email:
makerivictoria1234@gmail.com
DOI: 10.38177/AJBSR.2020.2205
Abstract: Citharinus citharus, Heterobranchus bidorsalis, Synodontis clarias and
Heterotis niloticus were examined for Endoparasites from June to January. A sample
size of 160 fish each, for the four fish species were analysed. Two species of
parasites were recovered; Eustrongylides sp (Nematode) and D. latum (Cestode).
Eustrongylides sp. was prevalent > 90% in all the fish species. All the parasites
were recovered from the gastrointestinal tract. Synodontis clarias had the highest
mean parasites load of 5.27. 78 ± 0.75 in the stomach and 2.85 ± 0.49 in the intestine
during the dry season.
Keywords: Synodontis clarias, Parasites, Eustrongylides, Gastrointestinal, Dry and
Wet Seasons.
Received: 13 January 2020 Accepted: 19 May 2020 Published: 07 June 2020

2. Asian Journal of Basic Science & Research
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Preparation of Specimens
A total of 640 specimens of fish belonging to four families; Citharinus citharus
(Citharinidae), Heterobranchus bidorsalis (Claridae), Synodontis clarias (Mochokidae) and
Heterotis niloticus (Osteoglossidae) were transported in water jars to the laboratory,
fisheries Department, University of Agriculture, Makurdi. Body parameters were taken. The
ventral surface of fish was cut open from the mid ventral position of the body at the anal
region to the mouth for examination of Endoparasites. The surface lining of the body cavity
outer surface of visceral organs; stomach, intestine, liver were examined for encysted
larvae and helminths. The organs were removed split open by a pair of scissors and the blunt
end of the scalpel used to scrap to dislodge the parasite and put in a 0.75 of Saline solution.
The recovered parasites were identified using the keys of Paperna (1991) and Paulder et al.
(2011).
Data Analysis
The prevalence of parasites was analysed in percentages. T-test, was used for differences
between the means. All data was analysed using minitab, 17th
edition.
Results
Prevalent Endo-parasites
The result of prevalent parasites in the four fish species is presented in the Histogram
(Fig.1). Two parasites Eustrongylides sp. (Nematode) and D. latum (Cestode) were isolated.
Eustrongylides sp. was prevalent at 97.5% in Heterobranchus bidorsalis, 95.6% Heterotis
niloticus, 91.3% Citharinus citharus and 90.7% Synodontis clarias. Mean while D. latum
(Cestode) was prevalent at 9.3% Synodontis clarias, 8.7% Citharinus citharus, 4.4%
Heterotis niloticus, and 2.5%. Meanwhile, D. latum was prevalent at 9.3% Syndontis clarias,
8.7% Citharinus citharus, 4.4% Heterotis niloticus, and 2.5% Heterobranchus bidorsalis.
Percentageprevalence
ofparasite(%)
Parasite and fish species

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Seasonal Variation in Length of Fish
Table 1 shows 160 specimen of each fish species consisted of different size groups. The
mean length of Citharinus citharus was 28.07 ± 0.8 (dry) and 26.97 ± 0.82 (wet).
Heterobranchus bidorsalis 2.0 ± . 0(dry) and 6.76 ± .0 (wet). In Synodontis clarias
mean length was 28.76 ± 0.7 (dry) and 27.76 ± 0.7 (wet) mean while Heterotis niloticus had
mean length of 0.40 ± 0.82(dry) and 29.05 ± 0.75(wet). This result indicate that variation in
mean length was statistically significant in Heterobranchus bidorsalis since P<0.01. This
shows that length in the species varied with seasons. All other results were not statistically
significant hence P>0.01. It also shows that Citharinus citharus, Synodontis clarias and
Heterotis niloticus had higher mean lengths in the dry season while Heterobranchus
bidorsalis had higher mean length in the wet season.
Seasonal Variation of Body Weight
In Table 1, the mean body weight of the fish species shows that Citharinus citharus had
mean body weight of 29 . 0 ± . 0 (dry) and 267.20 ± .20 (wet). Heterobranchus
bidorsalis had mean body weight of 49 .90 ± . 0 (dry) and 6 .40 ± 4.70 (wet). In
Synodontis clarias mean weight was 459.80 ± 2 .50(dry) and 46.40 ± 7. 0 (wet). Heterotis
niloticus had mean weight of 88.70 ± 2 .00 (dry) and 256. 0 ± 20.50 (wet). This result
indicates that C. citharus, S. Clarias and H. niloticus had higher mean weight in the dry
season. While H. bidorsalis had higher mean weight in the wet season. Seasonal variation of
mean weight in H. bidorsalis and Synodontis clarias were statistically significant at P<0.01.
Table 1: Seasonal Variation in Length and Weight of Fish
Fish species Sample Length Weight
Dry Wet PV Dry Wet PV
Citharinus
citharus
160 28.870.81 26.970.82 0.10 ns
293.1011.10 267.2011.30 0.10ns
Heterobranchus
bidorsalis
160 32.011.10 36.761.01 <0.01** 491.9031.70 631.4034.70 <0.01**
Synodontis
clarias
160 28.660.80 27.770.63 0.38ns
459.8023.50 346.4017.10 <0.01**
Heterotis
niloticus
160 30.400.82 29.050.75 0.22ns
388.7023.00 256.3020.50 0.29ns
** indicates statistically significant at 99% CL; * indicates statistically significant at 95% CL
ns indicate not significant.

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Seasonal Variation of Parasites in Stomach
The result in Table 2 shows that in C. citharus mean parasite load was .88 ± 0.4 (dry) and
.6 ± 048 (wet). S. clarias had mean parasite load of 5.27 ± 0.90 (dry) and . 8 ± 0.65 (wet).
H. niloticus had mean parasite load of .65 ± 0.45 (dry) and 0.77 ± 0. (wet). Parasite
infection in the stomach of H. bidorsalis was statistically significant P<0.05. This shows that
parasite load in the stomach varied with seasons. All the other result were not significant at
P<0.05. However, the result shows that parasitic infection was more in the dry season in all
the fish species.
Seasonal Variation of Parasite in Intestine
Table 2 shows that C. citharus had mean parasitic load of 0.77 ± 0. 8 (dry) and 0.68 ±
0.20(wet). In H. bidorsalis, the mean load was 2.60 ± 0.47(dry) and 0.78 ± 0.20(wet). S. clarias
had 2.85 ± 0.49(dry) and .67 ± 0. 6(wet). In H. niloticus mean load was 0.75 ± 0.2 (dry) and
0.76 ± 0. (wet). Intestinal parasites showed significant difference in the means of H.
bidorsalis P<0.01 and S. clarias P<0.05. Intestinal parasites were higher in S. clarias, H.
bidorsalis and C. citharus during the dry season.
Table 2: Seasonal Variation of Parasite Load in the Stomach and Intestine of Fish
Fish species Sample Stomach Intestine
Dry Wet PV Dry Wet PV
C. citharus 160 1.880.43 1.630.48 0.70 ns
0.770.18 0.680.20 0.75ns
H.
bidorsalis
160 0.420.72 2.220.52 <0.04* 2.600.47 0.780.20 <0.01**
S. clarias 160 5.270.90 3.180.65 0.06ns
2.850.49 1.670.36 <0.05*
H. niloticus 160 1.650.45 0.770.31 0.11ns
0.750.21 0.760.31 0.9ns
** indicates statistically significant at 99% CL; * indicates statistically significant at 95% CL
ns indicate not significant.
Discussion
The study recorded high prevalence of Eustrongylites sp. (>90.00%) in all the fish species.
Similar result was reported by Shola et al. (2016) on Bagrus filamentosus and Citharinus
citharus in both the stomach and intestine. Fishes in the study had mean standard length
range of 27.00cm – 34.00cm. This is slightly higher than the one reported by Omeji (2012)

5. Asian Journal of Basic Science & Research
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that O. Occidentals and Synodontis clarias within the standard length range of 22 – 28cm,
had higher prevalence of gastro intestinal helminth parasites. Other workers reported
length range of below 29.00cm in Citharinus citharus (Shola et al., 2016) 19 – 21cm on 48
fish species examined in Lake Uba and Ruwe Tanzania (Chacha, 2014), 20 – 30cm in C.
gariepinus (Kawe et al., 2016). Bagge et al. (2004) however stated that it is the host
population size that matters or shapes the parasite population size but not the host body
size or density. Fishes in the dry season were slightly longer than those in the wet season
though it was not statistically significant. In H. bidorsalis mean length was higher in the wet
season than in the dry season. This could be due to random sampling.
Fishes with body weight range between 500 – 600g have been reported for high prevalence
of parasite which is similar to the findings in this work (Kawe et al., 2016). Fish in the dry
season had higher mean weight than those in the rainy season. This shows that weight is
related to length. Higher mean value of parasites in Synodontis clarias agrees with the
findings of Iyaji and Yaro (2016) who reported high prevalence of helminth parasite in
Synodontis sp. at Lokoja. Auta et al. (1999) reported high prevalence in Zaria Dam. In this
study all the parasites were recovered from the gastro intestinal tract. This agrees with
Goselle et al. (2008) those helminth parasites have preference for regions of attachment in
the alimentary canal.
Higher mean parasite infection occurred in the dry season in both stomach and intestine.
This is in agreement with Asifa et al. (2016) who reported positive correlation between
parasite and seasons. Fish condition was high since P<0.01. The higher mean values were in
the dry season, which means that they were in a better fitness during the period similar
results were reported by Keri et al., (2011) on Oreochromis niloticus.
Conclusion
A sample of 160 fish each for four fish species were examined for variation of parasites load
in the dry and wet seasons. Two species of parasites, Eustrongylides sp. (nematode) and D.
latum (cestode) were recovered from gastrointestinal tract of all the fish species.
Synodontis clarias had the highest mean parasite load of 5.270.90 and 2.850.49 in the
stomach and intestine respectively during the dry season.
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